The C min Prelude of Book 1 finds a parallel in Wilhelm Friedemann Bach's Clavierbüchlein (keyboard booklet) and, as Ledbetter points out, it is quite clearly an exercise to make all fingers of both hands busy (which, today, may seem nothing special, but at JSBs time it was a rather modern concept).

Like the C major Prelude, the C minor P introduces a rather simplistic chord progression, which can be summarized in generic terms (without representing a 1:1 transcription) as follows:

As can be seen, the chords and their function do not pose material issues to understand what is going on. Also, there is very limited thematic development. Thus, the key to play the piece properly lies in choosing the tempo and achieve a proper articulation. Interestingly, the Prelude has been given tempo indications by JSB, in the sense that bar 28 introduces presto, bar 34 adagio, and bar 35 allegro. Such tempo indications are quite rare in JSBs keyboard music, and they are therefore practically always important.

My view is that presto means very quick, but not as quick as possible. This is not a Liszt etude, but a baroque prelude to a fugue. Therefore, even in the presto section, performers have to control their virtuosity and avoid overdoing it. Likewise, if bars 28f should be played very fast (Presto), then the parts before it should be slower than presto, and there should be a contrast, which means that the rhapsodic chords up to the presto should be quite a bit slower than presto itself. However, there are many interpreters that start the prelude in a rush, only to have little reserves to realize a presto which is distinct from the preceding part.

Here are some fingerings that work for me for the presto section (please select zoom in to see details):

Another aspect that is essential in the interpretation - the adagio and allegro sections form a recitativo. Which means that we should not try to find a beat which we can then follow slavishly, but to treat bars 34 - 38 as a section that provides freedom of expression. This freedom should be used in the most natural way, like finalizing a speech. Most records provide a very good closing section of the piece, so it is easy to get input.

My favorite recording of the piece comes from Friedrich Gulda, who achieves a remarkably calm and rather subdued intro section and therefore a contrasting presto. Angela Hewitt is the opposite case, her intro section and her presto is presented without great difference in tempo (121/144 BPM) and therefore hardly convincing (similar Leonhard). The presto loses a lot of momentum if we are already in the middle of a fast train at the beginning of the piece. Fellner, Stadtfeld, Richter and others start up quite agitated, but have the technical resources to run the presto even faster (and thus overdoing it? - hard to say). This is even more true for Hantai, who reaches 182 BPM in the presto (compare to Leonhard: 114 BPM). Interesting that while this sounds almost too fast (prestissimo rather than presto), Hantai manages to create a very convincing and dramatic effect, cleverly exploiting the harpsichords sound possibilities - I like it. Very convincing Schiff's 2012 version, medium tempo and a wonderfully clear and controlled presto - a must hear.

Well Tempered Clavier Book I: Fugue C minor

Fugue Book 1 C minor is an elegant and well balanced piece, which draws its fascination of its pure structure and the beauty of the interaction between the subject and the countersubjects.

Below is a graph of what happens structurally in the fugue - omitting the countersubjects, in order to provide a better overview:

As one can see, the overall structure is very clear: The fugue starts with a straightforward exposition, introducing the subject first in the middle, then in the soprano and finally the bass voice. The brief episode 1 in bar 5 and 6 serves to bring the flow back to Cmin. What follows is a series of subject entries in the development, each followed by a brief episode, until the fugue reaches its coda.

Bar 3 introcudes the first countersubject, which consists of a straight (inverted) melodic minor line downwards. The second countersubject is already rhythmically indicated in the second half of first countersubject , and appears the first time in its full version in bar 7 (middle voice). To make this clearer, in bar 15 (e.g.) one can see the subject and the 2 countersubjects interacting with each other (Subj.: Middle voice; CS1: Soprano; CS2: Bass).

if you go through the score, it is quite easy to see that the entries of the subject in the development sections regularly trigger the entry of both countersubjects, the voice of which depend on in which voice the subject enters. Further, the episodes use motives derived from the subject and the countersubjects to further increase the counterpoint effects.

From an harmonic perspective, the fugue does not create surprises. What is notable though is the quite strong emphasis on minor keys, which are left only very briefly. This creates a slightly dramatic element, particularly in bars 15 towards the end (maybe with the exception of the first part of Episode 5).

In my view, one can take this thought a step further and relate it to the overall tension map of the fugue. If we look in more detail, we can derive more out of the overall design than merely an exposition, then a couple of subject entries (with episodes in between) and finally the coda. The key to this fugue lies in the sequence of subject entries in the development section, which is asymmetric: Instead of 3 subject entries in the development, we have 4, the first three of which enter in soprano, alt and soprano. JS Bach therefore introduces a soprano subject entry in bar 20, where one might have expected a bass entry. This creates a certain tension, which is tamed at first by the rather innocent entry of Episode 5, only to be increased again when Episode 5 introduces the inversion of CS 1 (running upwards), with some rather strict chord type soprano and middle voice entries - all of this is preparing the subject entry in the bass. The latter - as a special feature - enters (again delayed) in the second half of bar 26, and increases the tension further by leading into an unfinished cadence towards the first inversion of C min in 28 (with a rather dramatic moment of silence), before resolving the flow (finally) with a straightforward cadence into the coda, which enters with a strong organ point on C in bar 29. In this context, one might say that the "waiting" for the entry of the subject in the bass is structurally increased by the increasing length of the episodes in the development (E3: 2 bars, E4: 3 bars, E 5: 4 bars), which further emphasizes the "delay effect" mentioned above.

Of course I am aware that this structural tension element is not comparable to the building up of tension in the Liszt sonata, and one should by no means overdo it. However, if the performer is conscious of the structural "delay effects" which the soprano subject entry in bar 20 introduces, and knows how to exploit those, this can help to increase the overall convincingness of the interpretation.

From a technical perspective, I do not see particular difficulties in this fugue, so no need to go into details regarding fingerings.

This fugue is played very convincingly by many performers, so there are many good recordings to chose from. Interesting that Gulda plays the fugue very slow (at 59 - Jando at 95 almost double tempo), and thus plays a similar tempo as Barenboim (56), but the character of the interpretations is totally different. Barenboim starts up with beautiful tone and "ambience", in stylo romantico (if I may say so), but later (unfortunately) varies the tempo (with no apparent good reason). Anyways, if I had to chose, I would vote for Gould and Schiff 2012 as my favorites.